城市湖泊富营养化成因和特征

城市湖泊的功能主要体现在旅游、娱乐、洪涝调蓄排水、调节气候以及改善城市生态环境等方向。根据湖泊所处地理位置和湖泊水质退化现象，阐述了城市湖泊水体从贫营养到富营养转变的主要原因：从水质的理化指标、底质污染物含量和水生态系统等方面初步讨论了城市型浅水湖泊富营养化的特征。同非城市湖泊相比：大部分城市湖泊的水体透明度下降，污染严重的湖泊还会出现水体发黑或出现水华：水质和底质的氮磷及其它污染物含量较高，水生态系统急剧退化，水生植物以浮游植物为主，藻类大量繁殖，高等水生植物不断消亡。根据综合营养度指数对我国主要城市湖泊进行分级评价的结果表明，我凼城市湖泊均达到了富营养化或严重富营养化程度。

Causes and characteristics of eutrophication in urban lakes

The urban lakes act as function of tourism, entertainment, drainage, climate modulation and environment improvement. The present paper describes the causes for the changes of urban lakes from oligotrophic to eutrophic status based on location and water quality degradation. Characteristics of eutrophication in urban lakes are discussed based on water quality index, contaminant concentration in. sediment and aquatic ecosystem. Compared with the other lakes, water in urban lakes is turbid, with lower transparency. Contents of nutrients and the other contaminants in water and sediment are usually higher. As aquatic ecosystem degrades rapidly, phytoplanktou become dominant producers, whereas macrophytes go to extinction. According to trofic state index, the pollution state of urban lakes in China is eutrophic or serious eutrophic.